Now that there's a few years to have built up knowledge on this, is it a good time to ask what options bigger (more powerful) than .308 based actually work in the standard large frame AR format? I've seen boutique stuff mentioned here and there but nothing seemed to really get traction. SAUM supposedly was made but not for very long and parts scarce--break an extractor and you're screwed. One-offs in WSM's listed out of stock forever or priced like a motorcycle. Is there anything yet that I can get and not be in a quagmire? 284 maybe?